Nonlinear Analysis And Parameter Optimization Of The External Hoop Nodes For Light Steel

Nowadays,with the development and application of reinforcement and reconstruction technology RC frame-light steel storey-adding structure is widely used and has a good development prospect.However,the method of traditional joint can not effectively solve the problem of sudden change in stiffness,and the joint form of upper and lower structures still needs to be studied and improved.In this paper,according to the characteristics of RC frame-light steel storied structure,a new type of external hoop joint is proposed,and its seismic performance is studied.The research results hope to have some reference for practical engineering.The main contents of this paper are as follows:(1)Review the relevant literatures of the existing building reinforcement and reinforcement technology,and give the design dimensions of the new external hoop node.Combined with the test results of the research group,the ABAQUS finite element software is used to establish a refined finite element model of the new external hoop node.In-depth analysis of the anti-seismic mechanism and failure mode of the new external hoop joints,and concluded that the new outer hoop joint has good bearing capacity,plastic deformation capacity and energy consumption,and can move the plastic hinge from the root of the beam to the steel.At the edge of the bottom of the column,the range and stiffness of the core area of the node become larger,effectively protecting the core area,ensuring the continuity of the vertical force transmission path,enabling more effective control of the crack development of the concrete beam and delaying structural damage.It is beneficial to improve the bearing capacity and overall seismic performance of the joints,and is in line with the seismic design principle of"strong columns and weak beams".At the same time,the correctness of the finite element model is verified by coMParison with the joint test results,which can be used for subsequent related parameter research.(2)The influence of relevant parameters on the seismic performance of the new external hoop joints was studied.By changing the steel model,the influence of the upper steel column model on the seismic performance of the joint is studied.The design suggestion is put forward:under the premise of ensuring the design requirements,the Q345 steel can be used to reduce the cost of the steel;by studying the hoop ratio and longitudinal of the reinforced concrete beam The influence of the reinforcement ratio of the ribs on the seismic performance of the joints leads to the conclusion that when the hoop hoop ratio of the reinforced concrete beam satisfies the structural requirements and the longitudinal reinforcement ratio is maintained within the range of 0.79%～1.40%,the test piece has Good bearing capacity,plastic deformation capacity and ductility;by studying the influence of the thickness of the column bottom plate and the outer hoop plate on the seismic performance of the joint,the design proposal is proposed:when designing the column bottom plate and the outer hoop plate,the thickness only needs to be satisfied.The stiffness requirements and construction requirements can meet the seismic requirements of the joint,which can save the amount of steel.(3)The effects of different parameters on the seismic performance and failure mode of the new external hoop joints are summarized,and the parameters optimization range that affects the seismic performance of the new joints is given.The parameters of the node parameters optimized by parameters are designed,and the finite element after parameter optimization is established.The model,through coMParison with the model before optimization,shows that the parameters optimized parameters can effectively improve the bearing capacity,energy consumption,stiffness and ductility of the new external hoop node in each loading stage,and the material utilization rate of the test piece.And the flexural bearing capacity,the seismic performance of the joint has been significantly improved and improved,and further indicates that the design proposal proposed in the paper is reasonable and feasible,and can be used to guide the actual engineering design.